Arthur T Knackerbracket has found the following story:
Terahertz radiation is used for security checks at airports, for medical examinations and also for quality checks in industry. However, radiation in the terahertz range is extremely difficult to generate. Scientists at TU Wien have now succeeded in developing a terahertz radiation source that breaks several records: it is extremely efficient, and its spectrum is very broad—it generates different wavelengths from the entire terahertz range. This opens up the possibility of creating short radiation pulses with extremely high radiation intensity. The new terahertz technology has now been presented in the journal Nature Communications.
More information: Anastasios D. Koulouklidis et al. Observation of extremely efficient terahertz generation from mid-infrared two-color laser filaments, Nature Communications (2020). DOI: 10.1038/s41467-019-14206-x
Journal information: Nature Communications
(Score: 2) by Booga1 on Tuesday January 21 2020, @06:10PM
Not quite handheld, but they do have the vans: https://www.homelandsecurity-technology.com/projects/z-backscatter-van-zbv/ [homelandsecurity-technology.com]
NYPD has a few, supposedly used for scanning empty vehicles, probably for drugs but only they know for sure: https://en.wikipedia.org/wiki/NYPD_X-ray_vans [wikipedia.org]